1. Field of Invention
The invention relates to a light-emitting diode (LED) apparatus having a micro- or nano-structure and a manufacturing method thereof
2. Related Art
A light-emitting diode (LED) apparatus is a lighting apparatus made of semiconductor materials. The LED apparatus pertains to a cold lighting apparatus, has the advantage of the low power consumption, the long lifetime, the high response speed and the small size and can be manufactured into an extremely small or array-type apparatus. With the continuous progress of the recent technology, the LED apparatus can be applicable to an indicator of a computer or a home appliance product, a backlight source of a liquid crystal display (LCD) apparatus, a traffic sign or a vehicle indicator.
However, the current LED apparatus still has the problems of the poor light-emitting efficiency and the low luminance. The reason causing the poor light-emitting efficiency is that the light emitted from the LED apparatus is the omni-direction light and is not simply focused on a certain location. In addition, only a portion of the light .generated by the LED can be outputted, and the other portion of the light is absorbed due to reflection. Consequently, the luminance of the LED apparatus is decreased, and the heat generated by the LED apparatus is also increased.
In general, the LED apparatus may be a flip-chip type LED apparatus, a vertical type LED apparatus or a front-side type LED apparatus. In order to solve the problem of the low light emitting efficiency caused by the reflection, the following technology has been proposed. As shown in FIG. 1, a LED apparatus 1, such as a vertical type LED apparatus, has an n-type semiconductor doping layer 121, an active layer 122 and a p-type semiconductor doping layer 123 sequentially formed on a surface of a substrate 11. Next, a current spreading layer 13 is formed on the p-type semiconductor doping layer 123, and a first electrode 14 and a second electrode 15 are respectively formed on the current spreading layer 13 and the other surface of the substrate 11.
As shown in FIG. 1, a light output surface 131 of the current spreading layer 13 is etched to form a roughing surface by a photo process in conjunction with the etching technology. Thus, the condition of the total reflection of light on the light output surface can be alleviated, and the light extracting efficiency can be increased.
Although the above-mentioned solution can solve the problem of the total reflection, the photo process and the etching technology have to be performed using expensive manufacturing apparatuses so that the manufacturing cost is increased. In addition, the structure of the above-mentioned LED apparatus also has the drawback of the poor thermoconductive property.
Therefore, there is a need to provide a light-emitting diode (LED) apparatus and a manufacturing method capable of decreasing the manufacturing cost and increasing the thermoconductive efficiency.